If you need a very small PC capable of running Windows 7 then a nettop is going to be your best bet and they just keep getting smaller. Japanese manufacturer Mouse Computer has managed to cram an Atom nettop sporting Nvidia ION graphics inside a case that’s just 20mm thick.

For 34,800 Yen, or $377, the Lm-Mini20 has an Atom 230 processor running at 1.6GHz, 1GB PC2-5300 RAM, 160GB hard drive, and Nvidia ION. Another nice option is the ability to upgrade the RAM to 3GB which is sure to make for a more pleasant Windows experience and larger hard drives are available. The operating system shipped is Windows 7 Home Premium.

The nettop is supplied with a stand, but can also be VESA mounted on to the back of a monitor. Connections include two USB 2.0 ports, audio and headphones out. Its full dimensions are 153.5 x 172.5 x 20mm.

At the moment it looks as though the Lm-Mini20 is only available in Japan.

I thought my home made nettop was really small and quite a squeeze to fit everything in the case, but the Lm-Mini20 shows you just how tiny you can go with the Atom platform. I suspect the system will get very hot due to the combination of the Atom and ION under a heatsink. As the case is so thin it’s not going to be a particularly large heat sink so the chips will ramp up to about 60/70 degrees. That’s not a problem for operation, but it might be like having a mini-heater on the desk.

The price isn’t particularly low, but it does come in slightly cheaper than the Asus Eee Box carrying a similar configuration and is significantly thinner. It’s the ION chipset that takes the price up with non-ION nettops sitting around the $200 mark. I would definitely opt for ION again if building another nettop.

Hopefully Mouse will offer the Lm-Mini20 overseas as it looks to be a very nice back-of-the-monitor solution.